As is known, when taking part in alpine skiing, the skier's boot is held securely with respect to the board by means of a safety binding composed of a toe stop located at the front of the boot and a heel binding holding the heel. The bindings are located on the ski in a zone defined normally as the "binding-fitting zone". This zone is centered with respect to the point of fitting the boot corresponding to the boot's mid-point. Its length is between 30% and 50% of the bearing length of the ski as a function of the size of the ski.
Many skis are sharply waisted and are thus relatively narrow in the median zone corresponding to the zone for fitting the binding.
Due to this narrowness the boot comes into contact with the snow when the ski is sharply tilted during turning stages. To solve this problem, it has been proposed to equip skis with a raised platform on which the two toe-stop and heel-binding parts of the binding are fitted.
Examples of such platforms are described particularly in documents FR 2 105 801, U.S. Pat. No. 3,260,532 and FR 2 409 776.
These platforms present a number of drawbacks, including, inter alia, their weight and their cost. The platforms stiffen the skis and result in a loss of energy at a time when momentum is required for turning. This loss is due to the stacking of mechanical components, the different mechanical clearances and flexions in the suspended parts.
In the initial stage of a turn, the skier exerts forces essentially at the front of the binding. When the momentum is required, these loads are transmitted by the board as far as the snow at the edges of the skis and, more precisely, onto the edges on the inside of the turn.
Thus, at the time of this momentum, the ski deforms and, more precisely, bends principally in flexion.
It is important for the ski to retain its inherent deformation characteristics even when it is equipped with safety bindings and the skier's boot. The ski's tendency to deform affects its behavior, i.e. its precision, grip, speed, comfort, etc. It is directly linked to the intensity and direction of the forces exerted on the ski by the skier. Deformation of the ski depends on the inner structure of the ski and its geometry, particularly its profile and variation in thickness, each ski preferably being designed for a specific type of use: long turns, short turns, powder, etc.
It is thus important not to unduly disrupt the behavior of a ski by equipping it with rigid devices such as bindings and platforms.
Moreover, when momentum is exerted on the ski, a deformation is propagated along the structure of the ski as a function of the board's inherent stiffness. The propagation of this deformation, equivalent to a vibration of the board, gives rise, in the zone of contact between the ski and the snow, i.e. the edges, to an oscillatory variation in the contact pressure.
In practice, this translates into jolting in the bearing zone, commonly known as "chattering", which disrupts the behavior of the turn and thus the precision of the ski which itself affects skier safety.